The Lake Tahoe Basin is world renowned for its natural beauty, water clarity, and winter sports activities. However, the increasing resident population and visitor use require clear roadways during the winter and hence the application of anti-icing and de-icing salts. During 1990, salt effects on vegetation adjacent to highways in the Tahoe Basin were studied. 15% of trees were salt-affected, but 1/3 of these trees had evidence for other damage. 30% of trees exhibited damage from non-salt related causes, and 55% did not exhibit any symptoms of salt, drought, disease, insect, or other damage. Thus, salts negatively impact roadside vegetation, but previous drought conditions may have made plants more susceptible to salt injury. Furthermore, salt content of soils was not abnormally high. Thus, although salts play some role in roadside vegetation damage, existing data from the Tahoe Basin also suggest that the role may be minor.

Comparisons of results from our new study with those obtained from the previous study will be used to evaluate the potential long-term impact of salts on roadside soil salinity, the health trends of vegetation along highways, and the maximum potential impact of salts on vegetation in the Tahoe Basin. Our improvements in sampling protocols (e.g. addition of new control plots, additional sampling of targeted soils and species) will strengthen the research and improve our ability to discern the damage due to salts.